Ultrasonic Testing

Ultrasonic Testing 

Ultrasonic Testing (UT) involves the use of short wavelength, high frequency acoustic waves to conduct inspections, examinations or to make measurements. The acoustic waves are mechanical vibrations that are transmitted by a small probe to a material by a probe, and when the waves encounter a change in medium it is reflected or refracted back to the same probe, or other probes.

The frequencies used in Ultrasonic Inspection are much higher than the human limit of hearing. Humans can usually hear between 20Hz to 20KHz, the frequencies used in Ultrasonics are between 500 KHz to 20 MHz.

How does Ultrasonic Testing work? 

Although different types of UT equipment exist, one commonly used system consists of a pulser and receiver, a transducer and an image display device. The Pulser / Receiver is a device that produces high voltage electrical signals. These signals drive the Transducer, which then produces high frequency ultrasonic energy. As the Transducer is placed onto the examination material, the ultrasonic energy propagates in the form of acoustic waves. As the waves propagate through the material, any change of medium such as defects (cracks) or the end of the material will reflect the waves back to the transducer, and be transformed back to an electrical signal and be displayed on the device.

Several different types of information can be gathered from an Ultrasonic examination including the wave velocity, travel time, reflector location, size, and orientation.

What applications is Ultrasonic Testing for?

UT is used at a variety of different industries including electrical power generation, the production of steel aluminum, titanium, aviation including fabrication, maintenance and overhaul, and ship building. It is also well known for medical applications such as diagnostic imaging and medical research. Ultrasonic can be used on a variety of materials, such as metals, plastics, ceramics and composites, this makes UT a very powerful volumetric inspection method.

What are the advantages of UT over other methods?
  1. A few of the advantages of Ultrasonic Testing include:

  2. The ability to detect both surface and subsurface discontinuities.

  3. The depth of penetration and measurement capabilities of UT systems are far superior than other NDT Methods.

  4. Minimum part preparation is required.

  5. Ultrasonic Testing provides fast almost instant results.

  6. Can be used for both flaw detection and thickness measurements.

  7. Compared to radiography, there are no health hazards associated with Ultrasonic Testing.

  8. Experienced and knowledgeable technicians paired with properly set-up and calibrated equipment, the results from a Ultrasonic Examination are highly accurate and repeatable.  

What are some limitations of UT over other methods?
  1.  While very powerful and useful, Ultrasonic Testing does have a few limitations including.

  2. The surface of the test specimen must be accessible to the instrument.

  3. The technician performing the inspection requires more training, experience and knowledge of Ultrasonic

  4. Inspection compared to other NDT methods.

  5. Ultrasonic testing requires a couplant medium that helps the transfer of sound energy to the test specimen.

  6. Materials that are porous or have complex make-ups could be difficult to inspect. This includes rough,irregularly shaped, thin and non-uniform materials 

  7. The use of reference standards is required for calibration of UT equipment, and for the interpretation of indications found during inspection. 

Have a question about Ultrasonic Inspection or about our services? We look forward to hearing from you. 

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